干湿循环过程中压实黄土的胀缩变形特性研究

为了研究干湿循环过程中压实黄土的胀缩变形特征,利用自主设计的黄土增减湿过程模拟装置,制备了初始含水率为10 %,干密度分别为1.45、1.55、1.65 g/cm³的土柱,首先将其浸水饱和,然后在自然条件下干燥收缩至初始状态,如此进行3次反复干湿循环试验。结果表明:浸水直至土体饱和过程中,土体会持续膨胀,膨胀应变ε随时间呈三段式增长现象;自然蒸发减湿过程中,土体体积随时间逐渐减小。干湿循环过程中,吸力随时间变化经历微弱变化期-急速变化期-平稳期3个阶段,且与土体胀缩应变呈对应关系。通过整理试验数据分别得到了土体浸水膨胀阶段应变ε和收缩阶段孔隙比与基质吸力的拟合关系,能够很好的表征压实黄土的胀缩变形特性。

Study on the Swelling Shrinkage Deformation Characteristics of Compacted Loess during the Drying and Wetting Cycles

In order to study the swelling and shrinking deformation characteristics of compacted loess in the process of dry and wet cycles, the soil columns with initial moisture content of 10% and dry density of 1.45, 1.55 and 1.65 g/cm³ were prepared by using the self-designed simulation device of loess wetting and drying process. Firstly, the columns were saturated with water, and then dried and contracted to the initial state under the natural condition. In this way, three repeated dry and wet cycles tests were carried out. The results show that the soil will continue to expand and the expansion strain ε will increase in three stages with time in the process of soaking until the soil is saturated, and the soil volume will gradually decrease with time in the process of natural evaporation and dehumidification. In the dry and wet cycle, the suction changes with time in three stages: weak change stage, rapid change stage and stable stage, and it has a corresponding relationship with the soil swelling and shrinkage strain. Through sorting out the test data, the fitting relationship between the strain ε and the void ratio of the soil in the swelling stage and the shrinkage stage and the matric suction is obtained, which can well represent the swelling shrinkage deformation characteristics of the compacted loess.